1. Field of the Invention
The present invention is directed to the field of starter motors for internal combustion engines and more specifically to the area of providing a watertight seal between the housing and the engageable gearing that interconnects the starter motor to the engine.
2. Description of the Prior Art
Several prior art patents have indicated the desirability of preventing dirt, water and other debris from entering the electric motor and solenoid portion of a starter motor for an internal combustion engine. The following patents all provide various sealing mechanisms intended to confine the contaminants to the pinion drive mechanism that is engageable with the drive gear on the engine.
U.S. Pat. No. 4,718,290 is directed to a starter motor for use in a lawn mower engine in which a horizontally oriented flywheel has a cooling fan attached that has a tendency to force foreign matter into the portion of the starter motor housing containing a vertically translatable pinion gear. A rigid wall extends from the internal portion of the housing towards the sleeve that envelopes an overrunning clutch. The wall contains a central hole which corresponds to the diameter of the clutch so as to allow the clutch to vertically reciprocate through the central hole of the wall. The inside surface of the wall is always in contact with the outside surface of the sleeve regardless of the position of the overrunning clutch.
U.S. Pat. No. 4,206,656 is directed to a starter motor which utilizes an internal cup-shaped wall to extend around an overriding clutch when it is in its retracted position. The cup-shaped wall contains a central aperture through which the sleeve of the overriding clutch extends throughout its reciprocating movement. The cup-shaped wall contains a resilient member surrounding the central aperture so as to be in continuous contact with the sleeve throughout its reciprocating movement.
U.S. Pat Nos. 4,104,926 and 3,955,427 describe a starter motor containing a resilient annular seal secured to the inside of the housing so as to encircle and make contact with the outer sleeve of an overrunning clutch. Throughout the reciprocating movement of the clutch, with the pinion gear, the resilient seal continually maintains contact with the outer sleeve.
U.S. Pat. No. 3,772,921 describes a starter motor in which an annular lip seal resides on the outer periphery of a translatable pinion gear so as to make contact with the concentric housing surrounding the pinion gear throughout its translation into and out of engagement with the driven gear on a associated engine.
In each of the prior art patents cited above, the sealing that occurs to prevent contaminants from entering the electrical motor and solenoid portions of the motor housing is provided to continually seal the moveable elements (clutch or pinion gear) during both their reciprocal axial translation and rotational movement after engagement with the driven gear of an engine.
It is believed that such continual sealing produces potential wear and degradation of the seal, drag on the motor, and potential seizing between the seal and the moveable elements Seizing is especially problematic in that the retraction of the pinion gear from engagement with the driven gear may be prevented.